A rocket is propelled with the aid of fuel and oxidizing agent. The fuel is generally propellant, which is contained in tanks and then distributed under cryogenic conditions in order to supply the thrusters in a precise manner, solenoid valves are connected to the tanks. The valves generally have electromagnetic actuators that utilize the current of the electric network of the rocket. The actuators must adapt to the amperage available over the network.
In order to keep an electromagnetic valve open, it is necessary to supply current continuously to the coil of the valve. However, the current that circulates there causes the valve to heat up, in some cases to as much as 100° C., which risks igniting the fuel.
The fuel and the propellant circulate in gaseous form and at a temperature reaching −200° C. and a pressure of approximately 400 bar. This pressure exerts destructive forces on the sealing elements, as do the mechanical vibrations of a rocket during take-off thereof. These vibrations can translate into accelerations of 60 g, which speed up the wear of sealing surfaces, together with the closing motion impacts.
Document FR 2 487 942 A1 discloses a valve with a distribution level and a regulation level of the distribution level. The distribution level comprises two balls cooperating with two opposite seats. A shaft disposed between these balls makes it possible to open and close them selectively, and a piston with bellows makes it possible to actuate one of these balls. The piston is controlled by the regulation level, which comprises two balls also connected by a shaft and held in a closed position by a spring. An electromagnetic actuator with a tappet plunger pushes one of the balls, which in turn pushes the other ball via the shaft.
This configuration is bulky. In addition, the ball cooperating with the plunger balls is exposed to significant forces, which degrade the seat of the ball, and therefore the seal deteriorates with use. Indeed, the closing motion means that the seat absorbs the kinetic energy of the plunger of the electromagnetic valve. At the same time, the tappet of the plunger is progressively work-hardened under force in order to crush the ball against its seat. Consequently, it is not possible to assure effective centring and correct plating of the ball towards its seat, and therefore the seal is again compromised. It would therefore be beneficial to propose a valve with a ball pushed from its seat from the corresponding orifice.